User manual

Part B Section Appendix A.4
18 LANDING TECHNIQUE (INTRODUCTION)
There is a particular angle of attack that for each seaplane produces the gentlest transition
from air to water. In Catalina’s that occurs at an airspeed of 72 knots. At that speed the
rear part of the hull near the step is the only that contacts the water. Deceleration forces
are behind the centre of gravity the situation is stable (like a tricycle undercarriage)
If speed is >80 knots the angle of attack is too low (flat attitude) and will cause the front of
the hull to contact the water. If the hull forward of the centre of gravity contacts first, the
deceleration forces are ahead of the CofG, an unstable configuration (like a tail dragger).
Turning forces may then be difficult to handle, resulting in a spectacular water loop. The
flat attitude also puts water impact forces on the nose wheel doors and these may collapse
or tear off with disastrous results.
If speed is <65 -70 knots the excessive nose up attitude will cause a skip or bounce in
most water conditions. This is not dangerous if the correct technique is followed and the all
important attitude is re-established. Do not lower the nose below the normal water landing
attitude. While not as dangerous as a fast approach it can be uncomfortable for all on
board.
Concentrate on aircraft nose attitude at all times. If landing in choppy conditions be-aware
that the nose will pitch up with the waves. Be ready to counter this with elevator as
required. Keep the attitude constant (nose up) throughout the time on the step and move
the controls steadily back as the aircraft slows. Controls should be hard back as the
aircraft come down off the step and must stay that way until the aircraft stops, (see below)
19 LANDING TECHNIQUE (POWER ASSISTED)
This is the Standard seaplane approach and landing technique for good conditions.
After completion of the approach checklist, manoeuvre to downwind with a minimum
speed of 95 kts. 20 seconds after passing abeam touch down point reduce power to 15 ins
and make speed 95 kts. Turn final and plan to be established on final at 300 ft AWL. While
turning final make a last check to confirm aircraft configuration “landing gear UP” Final
speed 85 kts. And power set at 12 ins. At flare altitude, flare and aim for touch with a
speed of 72 kts.
After the touch, slowly close the throttles and the aircraft will slow once on the water and
once below 50 knots it can not leave the water. As the aircraft slows the control column
needs to be eased steadily back and should be fully back as she comes down off the step.
Keeping the nose up protects the nose gear doors, and keeps the deceleration forces
behind the CofG, maximising control and minimising the risk of a water loop. This is
particularly important at the end of the landing run as the aircraft comes down off the step.
More water loops occur at this time than in the early part of the landing run.
The controls should be kept fully back until the aircraft comes to a complete stop.
After touch down at 72 knots the lower speeds at the end of the landing run feel very slow,
especially if conditions are choppy or rough and a bounce or two have occurred early on. It
is easy to relax as the speed decays and allow the controls to move forward thinking that
the aircraft is well off the step when in fact it is not or is only just, and still has significant
forward speed. This is a very risky time for water looping. Maintain concentration and keep
the controls hard back.
Stichting Catalina PH-PBY Rev No: 02
01 April, 2006 Page: 9